Sigma Photo Pro: what does the detail slider do?

I remember when after a long break from photography I bought my Sigma sd Quattro and installed SPP and that after starting the application the first thing that caught my eye was the new “detail” slider. In the spring of 2016, when I was still shooting with my SD1 Merrill and using a at the time up to date version of SPP, this slider wasn’t there. I was aware that it was meant for adjusting the level of micro contrast. But I didn’t have time to take a closer look at what it exactly does. Now I have done that.

With blog posts such as this one, where I discuss SPP and photo editing, I usually start with the context. I’m sure, that for you readers it is important to understand the workflow and especially the settings used, so that you can reproduce the results.

The photo of the construction site is an X3I file. It is cleaner than any X3F file could ever be, which is the reason I chose it. I wanted to see how far one can crank up micro contrast before luma noise starts to creep in. Sharpness was set to 0, which is way too much for motifs with straight lines and high contrast edges.

I have chosen the photo with the pears because that X3F has quite visible color blotches in the shadows and because I was interested to see how far we can boost micro contrast of a motif with irregular, organic patterns and easily visible noise.

All crops are from these two photos, which were developed several times with identical setting except for the detail slider.

You can find seven samples per photo on flickr – as many as there are settings on the detail slider. I have decided against making a composite of all the crops, because the differences between the individual settings on the detail slider are rather small. You have to look very closely to see any difference. It’s easier to see the differences when only comparing the settings „smooth“ and „crispy“. Those who are curios can take a look at the fourteen full res photos on flickr.

Now let’s take a look at the photo of the construction site. The upper crop is part of a JPG, which was developed with the detail slider set to smooth. With the lower one this setting was set to crispy.

What becomes immediately apparent is that the detail slider has a huge effect on not only micro contrast but luma noise as well. While you have to look for luma noise long and hard in the upper crop – we are talking about a X3I file, which consists of multiple captures, after all – it is quite apparent in the lower crop. Even though the micro contrast is very high, which is something landscapes benefit from quite a bit, I prefer the look of the “smooth” setting.

When it comes to the photo with the pears, I’m not sure which setting I prefer. On the one hand, the pulp looks better with the crispy setting (lower crop).

But on the other this setting increases luma noise in the shadows a lot, which is something one would like to avoid. Interestingly the algorithm has next to no effect on color blotches. Before doing this experiment, I was under the impression that higher micro contrast would have a more detrimental effect on color blotches than on luma noise.

Conclusion

In comparison to other sensors on the market the Quattro Foveon sensor offers very high micro contrast. This holds true even when you pull the detail slider all the way to the left (smooth setting). Therefore on has to ask oneself whether an even higher micro contrast isn’t overkill. What the answer to this question will look like depends on the photographer’s personal preferences and the motifs he or she shoots. I, for one, am going to use this slider the same way I use the sharpness slider. Which is according to the motto less is more. 🙂